READY TO WORK: Sandy Alderson, who will officially be named the Mets’ GM tomorrow, is as thorough in his approach as any baseball executive, colleagues say. Photo: Getty Images

Picking a new manager will almost certainly be Sandy Alderson’s most immediate task as the Mets’ new general manager, but that will be just the first step in what could be a vast overhaul of the organization.

“He’s going to build from the bottom up,” said Grady Fuson, who worked with Alderson in both Oakland and San Diego. “Obviously, he’s got to pick a manager and his own staff, but he’s not going to leave anything unturned all the way through the system.”

Alderson, who is expected to be named officially to the position tomorrow at Citi Field, is known throughout baseball for his attention to detail — one of the traits that made him so attractive to the Mets’ hierarchy.

“He is going to know everything that’s going on,” said another former colleague. “He’s better at that than anyone I’ve worked with.”

Throughout the GM search, former associates lauded Alderson’s willingness to be patient, something that won’t be easy to do in New York and across town from the Yankees’ perennial success. But those who have been around the 62-year-old are confident he has the ability to stick to his plans.

“He’s going to be involved in every phase of the organization,” said Fuson, who is now a special advisor to Billy Beane, Alderson’s successor as GM in Oakland. “He’s going to come in with a vision of where he wants the team to go and what the long-term effect of that will be.”

But he is also realistic enough to know that he won’t have an indefinite period of time to turn things around.

“He realizes that there are different expectations in New York,” Fuson said. “And that there should be no five-year rebuilding process when you have the resources the Mets do. People forget, in the late ‘80s, we were pretty much a big-market club, when we were putting rings on our fingers.”

And it’s those resources that Alderson didn’t have toward the end of his tenure as GM in Oakland or CEO in San Diego.

“It’s a totally different job when you have the revenue to work with that he’ll have with the Mets,” one former associate said. “But having the background of having dealt with a lack of revenue will only help him now. The things he learned from that will only make him better now, but he hasn’t swayed from his philosophies.”

And that’s why most people who have worked with Alderson are confident that the fact he hasn’t been a GM since leaving the A’s in 1997 won’t be an issue.

“He’s very engaged,” Fuson said. “He’ll read every game report from the minors every night. He’ll know every prospect by name, height and birthday. He’ll know the top 50 guys in the draft. He’ll have his hands on everything and won’t be blindsided by anything.”

As for his major first hire, Alderson was famously quoted in the book “Moneyball” as saying of managers: “Art Howe was hired to implement the ideas of the front office, not his own. And that was new.”

In the book, he was also quoted saying: “In what other business do you leave the fate of the organization to a middle manager?”

But people around baseball warn against the thought that he has only one type of candidate in mind.

“There will have to be open communication,” another source said. “But he’s more open to discussion than he used to be and he’s not going to just pick someone who only follows the company line. He’ll want someone who can think for themselves.”

* Omar Minaya’s role in the organization remains uncertain. The former GM is still taking time off to be with his family and those close to him said he has not decided what he is going to do once Alderson is officially hired — but has not ruled out the possibility of working for him.